Field of the Invention
The present invention relates to a CT-image processing apparatus and a method which process projection data in which an animal is captured as a subject at each time by an X-ray CT apparatus.
Description of the Related Art
X-ray CT imaging is effective for observing an inside of an animal such as a mouse or a rat. However, an animal cannot hold breath during CT imaging according to the instruction of an operator, like a human being. Further, a heart cannot be stopped in biometric imaging. Therefore, the image of an internal organ such as a heart, lungs, and the neighboring lever is blurred by the influence of heartbeat and breath and is not suitable for the accurate observation and test of a region.
To overcome this situation, there are known a method of obtaining a heartbeat signal using an ECG (electrocardiograph) to perform breathing beat synchronization, and a method of imaging a chest part of a small animal with a video-camera and obtaining breathing beat from the vibration of the chest part to perform the breathing beat synchronization. However, each of these methods needs dedicated apparatus or equipment and imposes a burden in the aspects of cost and operation.
A CT-image processing apparatus disclosed in Patent Literature 1 calculates specific information of a ROI for synchronization at each capturing angle so as to track a regio of a target subject to obtain a strong synchronization signal and measures a feature amount expressing a breathing beat or a heartbeat sufficiently well, and thereby enables simple synchronization processing to be performed by using projection data.